Cold Brew Coffee

Cold Brew Coffee

Cold brew refers to the process of steeping coffee grounds in room temperature or cold water for an extended period. Cold brew coffee is not the same as iced coffee. Iced coffee refers to coffee that is brewed hot and then chilled by pouring over or adding ice, though iced coffee can refer to cold brew coffee served on ice.

Cold brew coffee system
The cold-water-extract process requires grinding: coarse-ground beans are soaked in water for a prolonged period of time, usually 12 hours or more. The water is normally kept at room temperature, but chilled water can also be used. The grounds must be filtered out of the water after they have been steeped using a paper coffee filter, a fine metal sieve, a French press or felt. The result is a coffee concentrate that is often diluted with water or milk, and can be served hot, over ice, or blended with ice and other ingredients such as chocolate.

Purpose
As the coffee beans in cold water extract coffee never come into contact with heated water, the process of leeching flavor from the beans produces a different chemical profile from conventional brewing methods. Coffee beans contain a number of constituents, such as caffeine, oils, and fatty acids, which are highly soluble at high temperatures. By brewing the coffee at lower temperatures, many of these solubles do not completely dissolve, resulting in lower acidity and lower caffeine content when brewed in equal volume. (Wiki)

During the cold-brew process, time replaces heat. Todd Simpson, a chemical engineering graduate of Cornell, and who developed the Toddy cold brew system, discovered that high temperature facilitates the release of undesirable flavor elements.

A roasted coffee bean contains many compounds that are extracted during the brewing process. Some of those compounds, including certain oils and fatty acids, are soluble only at a high temperature. During the cold brew process, coffee beans are never exposed to high temperature (this only occurs after a rich liquid coffee concentrate has been produced).

Deceptively simple, cold water brewing extracts the delicious flavor compounds (and some of the caffeine) from coffee beans, but leaves behind myriad bitter oils and biting fatty acids, including undesirable elements such as ketones, esters and amides.

These are the same bitter acids and fatty oils that surface to the top of your hot cup of coffee, and give hot-brewed coffee that familiar ‘bite’ (thus the reason that some 8 out of 10 people attempt to soften the acidic taste by adding milk or cream to their coffee).